Lowell Observatory announced the discovery of Pluto
On this day · 13 March 1930
After a year of patient sky-blinking, a 24-year-old Kansan found a new world—and an observatory waited weeks to tell anyone.
On March 13, 1930, Lowell Observatory in Flagstaff, Arizona, told the world it had found a ninth planet. The discoverer was Clyde Tombaugh, a 24-year-old self-taught astronomer hired to hunt for the long-predicted “Planet X.”
Tombaugh actually spotted the object on February 18, 1930, by comparing photographic plates taken on January 23 and January 29 with a blink comparator—a device that flips between two images so a moving point seems to jump while the stars hold still. Confirmation took weeks, and the announcement date was chosen with care: it marked both Percival Lowell’s birthday and the anniversary of William Herschel’s discovery of Uranus.
Smaller than Mercury and billions of miles from the Sun, Pluto was a needle found in a haystack of stars.
The name Pluto, suggested by an 11-year-old English girl, was adopted on May 1. For over seven decades it ranked as the first body of what we now call the Kuiper Belt.
Sources & references
3 referencesWell-established. Corroborated by 3 independent sources.
